package day01_homework;

import java.util.Scanner;


public class Test02 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String name = sc.nextLine();
        int len = name.length();
        if (len == 0) {
            System.out.println("用户名不能为空");
        } else if (len > 20) {
            System.out.println("用户名必须在20个字以内");
        } else {
            System.out.println("用户名验证通过，名字为：" + name);
        }
    }
}
